"Concern about the ability to repay student debt is pervasive, and this early debt can have rippling effects over a life course, " says Signe-Mary McKernan, one of two authors of a new report from the Urban Institute called "Forever in Your Debt: Who has Student Loan Debt, and Who's Worried?"

And the profile of the typical debt holder is anything but typical. It's a varied group that includes young and old, white and non-white, men and women, low-income and high-income, according to the report.

The drastic change in student debt levels between 1989 and 2010 can be attributed to several factors, McKernan says.